1. Field of the Invention
The Present invention relates to a dry-etching method using a novel etching plasma.
2. Description of the Prior Art
Etching techniques are known in the art that involve selective removal of materials by an interaction with chemically reactive ion species created by a radio frequency (RF) power-induced glow discharge maintained in the etching chamber. Such reactive ion etching (RIE) is becoming increasingly important in state of the art micropatterning processes including etching of substrates such as semiconductor wafers and other workpieces including, e.g., etching of SiO.sub.2, SiC, Si.sub.3 N.sub.4, etching of passivation layers or diffusion barrier layers, and stripping of photoresists.
In a conventional RIE method, the surface of a substrate to be etched is covered with a mask leaving selected areas of the substrate exposed. The substrate is inserted into a chamber containing a chemically reactive gas, such as CF.sub.4, in admixture with O.sub.2. A plasma is created by applying an RF voltage across the gas to cause the gas to dissociate and form various species comprising positive and negative ions, reactive atoms, such as fluorine, and radicals. The plasma reacts with the surface and forms volatile products leaving an etched surface in the areas exposed by the mask.
The industry acceptance of RIE has been based partly on its ability to provide good etch selectivity and profiles. However, compared to other etching processes, RIE provides relatively low etching rates. To overcome such low etch rates, RIE usually requires batch processing for economically attractive throughput. This introduces problems of end-point detection, control of uniformity and complexity of implementation.
Thus, there is a need for increasing the etching rate of a reactive ion etching plasma which does not adversely affect the surface quality or chemical sensitivity of the etched substrate.